Multiple solutions

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Multiple solutions

Postby Joe Murray » Wed Dec 19, 2007 11:30 pm

I was given to believe that there was only one solution to each sudoku problem. In this mornings Wash Post (12/19/07) I found that there were two solutions, involving three 6/9 cells which could be resolved in two different ways.

Then when I entered the key five digits for that puzzle( 23629) to Sudoku.com, I was given a third solution to the puzzle--quite different except for the 5 digit (23629) generating key and the remaining digits of the key (54138527681864571278374). What gives? Ren't solutions unique? [Obviously I am new at this game.]
(
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Postby JL » Thu Dec 20, 2007 12:05 am

Would really help to know what the puzzle is. If it's the same as the one online, then the puzzle is valid. Here is the puzzle I found online:

Code: Select all
. 7 9|. . .|. . .
. 6 .|. . 8|. . 9
. 2 .|. 9 .|3 . .
-----+-----+-----
7 . .|8 . .|. 6 4
. . .|5 6 2|. . .
3 8 .|. . 7|. . 5
-----+-----+-----
. . 7|. 4 .|. 8 .
8 . .|6 . .|. 7 .
. . .|. . .|4 5 .


It is a very easy puzzle You may have simply made a mistake. [/code]
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re: Washington Post 23629 ( 2007.Dec.19 )

Postby Pat » Thu Dec 20, 2007 10:17 am

Joe Murray wrote:I was given to believe that there was only one solution to each sudoku problem. In this mornings Wash Post (12/19/07) I found that there were two solutions, involving three 6/9 cells which could be resolved in two different ways.

Then when I entered the key five digits for that puzzle( 23629) to Sudoku.com, I was given a third solution to the puzzle--quite different except for the 5 digit (23629) generating key and the remaining digits of the key (54138527681864571278374). What gives? Ren't solutions unique?


hi Joe Murray,

Pappocom puzzles always have exactly one answer,
however it is possible that The Washington Post misprinted the puzzle.

the puzzles printed in The Washington Post aren't available online,
it would help if you could post the original puzzle!

thanks
~ Pat
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Postby tarek » Thu Dec 20, 2007 11:08 am

I've checked the online Puzzle.... It is as JL said.

We must be talking about a different puzzle:idea:

tarek
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re(2): Washington Post 23629 ( 2007.Dec.19 )

Postby Pat » Thu Dec 20, 2007 11:41 am

OK i went and obtained 23629 as it should have been printed [ 28 clues ] --

Code: Select all
 2 . . | . . . | . . 3
 . 6 . | 2 9 . | . 5 .
 4 1 . | 3 . . | . . .
-------+-------+------
 . 8 . | . 5 2 | 7 . .
 6 . . | . . . | . . 8
 . . 1 | 8 6 . | . 4 .
-------+-------+------
 . . . | . . 5 | . 7 1
 . 2 . | . 7 8 | . 3 .
 7 . . | . . . | . . 4



-- exactly one answer of course
( and only "singles" needed )
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Re:multiple solutions

Postby Joe Murray » Thu Dec 20, 2007 8:49 pm

All of your replies are correct of course. Thank you. I indeed made a mistake. Usually when I do so, the whole puzzle crashes and it is obvious. In this case, row 2 of my solution had two 5's and row 3 had two 8's -- compensating errors -- so the crash was not obvious and since I was focussed on the 6 entries which could not be uniquely resolved, I missed it.

2 9 8 5 1 7 4 6 3
3 6 5 2 9 4 1 5 7
4 1 7 3 8 6 8 2 9
9 8 3 4 5 2 7 1 6
6 4 2 7 3 1 5 9 8
5 7 1 8 6 9 3 4 2
8 3 A B 4 5 2 7 1
1 2 4 A 7 8 B 3 5
7 5 B 1 2 3 A 8 4 where A's = 6 or 9 and B's = 9 or 6

Sorry for not checking my "solution" more thoroughly. But I still find the A/B 6/9 phenomenon interesting. Did it result from my previous error?

I am sorry now that I used Joe Murray's name without his permission as he will probably have to change his name and leave the forum.

Moe Jurray
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